A major challenge in both in vivo therapeutic (re)vascularization and in engineering vascularized tissue constructs ex vivo is establishing new capillary channels and maintaining them for extended periods of time. In the native microvasculature a unique cell population, termed "pericytes," is responsible for providing support signals to capillary endothelial cells and maintaining newly formed microvessels. Therefore, a prudent approach in "microvascular tissue engineering" and revascularization strategies is to identify a pericyte 'precursor'population that is easily obtainable, can be expanded ex vivo, is capable of being recruited to the ablumenal surface of the endothelium, and promotes and microvessel viability and longevity through recognized molecular mechanisms. Stromal cells obtained from adult human adipose tissue are readily available and easily harvested through minimally invasive liposuction and lipoectomy procedures. New data suggests that human adipose tissue contains a sub-population of self-renewing, multipotent stem cells (hASCs) that possess vast differentiation potential and an ability to augment microvascular growth in vivo in injured tissues. We have identified a pericyte-precursor sub-population of hASCs, and we have collected preliminary data to support that they behave like pericytes when injected in vivo, meaning that they express pericyte markers, migrate to the ablumenal surface of microvessels and alter their morphologies to conform to the curvatures of vessels, and enhance vascular length density. The goal of the proposed work is to understand the molecular mechanisms and cellular behaviors by which these hASCperiytes contribute to vascular growth in a pericyte-like manner so that this readily available source of therapeutic cells may be most effectively exploited in microvascular engineering and revascularization strategies following ischemic insult. Specifically, we propose to test the hypothesis that hASC-pericytes enhance microvascular maintenance during ischemia through pericyte-like mechanisms, and specifically PDGF-BB signaling, in the following specific aims: AIM 1: Quantify the migratory behaviors of hASCs in response to PDGF-BB signaling in vitro. AIM 2-Develop a multi-cell agent-based computational model, based on an established published model, to facilitate a systems-level interrogation molecular signals (in addition to PDGF-BB) modulating hASCparticipation in microvascular remodeling. AIM 3: In a novel whole mount model of muscle ischemia, inject GFP-labeled hASCs and track their behaviors in vivo.